A description is given of a prior art high definition graphic display apparatus with reference to FIGS. 7 to 10.
FIG. 7 is a block diagram illustrating the prior art high definition graphic display apparatus. In FIG. 7, a polygon data inputting unit 701 is for producing polygon data 711 comprising a coordinate of each vertex of a polygon to be displayed. An N times coordinate conversion unit 704 is for expanding each coordinate of the polygon data 711 N times to obtain N times polygon data 712. An active list producing unit 705 is for producing an active list 713 from the N times polygon data 712. A scan list producing unit 706 is for producing a scan list 714 from the active list 713. A rasterize unit 707 is for converting the scan list 714 into N times raster data 715. A 1/N time reducing unit 708 is for assuming N.times.N pixels in the N times raster data 715 as a cell and converting the N times raster data 715 into raster data 716 represented by an average which is obtained from averaging concentrations of the cell. A display device 709 is for displaying the input raster data 716. A polygon data expansion section 702 comprises the N times coordinate conversion unit 704, the active list producing unit 705, the scan list producing unit 706, the rasterize unit 707, and the 1/N time reducing unit 708. A display unit 703 comprises the display device 709.
FIG. 8(a) illustrates a polygon to be displayed. In the figure, reference numeral 800 designates the polygon to be displayed, reference numerals 801, 802, 803, 804, and 805 designate vertexes of the polygon 800, respectively and reference numerals 811, 812, 813, 814, and 815 designate sides of the polygon 800, respectively.
FIG. 8(b) illustrates a polygon which is expanded N times by the N times coordinate conversion unit 704. In the figure, reference numeral 8000 designates a polygon which is expanded N times, reference numerals 8010, 8020, 8030, 8040, and 8050 designate vertexes of the polygon 8000, respectively and reference numerals 8110, 8120, 8130, 8140, and 8150 designate sides of the polygon 8000, respectively.
A description is given of an operation of the prior art high definition graphic apparatus.
The polygon data inputting unit 701 produces polygon data 711 comprising coordinates of vertexes 801 to 805 of the polygon 800 to be displayed.
The N times coordinate conversion unit 704 expands respective coordinate values of vertexes of the polygon 800 which are written onto the polygon data 711 which is produced by the polygon data inputting unit 701, to produce N times polygon data 712. At this time, when the expansion ratio N used in the N times coordinate conversion unit 704 is set to be 4, every value of the vertex of the polygon data 711 is expanded 4 times and converted into N times (4 times) polygon data 712 comprising sides (8110, 8120, 8130, 8140, 8150) shown in FIG. 8(b).
FIG. 9 illustrates the active list 713 which is produced by the active list producing unit 705. In FIG. 9, reference numeral 901 designates a header of an active list, reference numeral 902 designates a header of a line active list of a Y coordinate line Y=0, reference numeral 903 designates a header of a line active list of a Y coordinate line Y=32, and reference numerals 911, 912, 921, 922, and 923 designate active cells corresponding to sides of the polygon, 8110, 8120, 8130, 8140, and 8150. The active list producing unit 705 scans Y coordinate lines of the polygon 8000 of the 4 times polygon data 712 in the order of ascending numerals from Y=0 and sequentially produces a line active list for a Y coordinate line which is an origin of a side of the polygon. For instance, when N times polygon data of the polygon 8000 is input, since there are sides 8110, and 8150, whose tops are present on X coordinate 12 on Y coordinate line Y=0, the active list producing unit 705 produces a header 902 of a line active list indicating Y=0, and then produces the line active list which describes active cells 911 and 912 comprising parameters such as an X coordinate which belongs to the top of the side, a number of Y coordinate lines which intersect the side, and inclination of the side. In addition, since there are sides 8120 and 8130 whose tops are present on X coordinate 16 on Y coordinate line Y=32 and a side 8140 whose top is present on X coordinate 36, the active list producing unit 705 produces a header 903 of a line active list indicating a line Y=32, and then produces the line active list which describes active cells 921, 922, and 923 corresponding to these sides. An active list 713 represented by the header of the active list and the following line active list for each Y coordinate line thus obtained are produced by the active list producing unit 705. As illustrated by a side 8150, when there is another side (in this case 8140) which is continuous with the side 8150 in the ascending order of Y coordinate, the number of Y coordinate lines of an active cell 912 corresponding to the side 8150 which intersect the side 8150 is smaller than a number which is computed using vertex coordinate by 1.
FIGS. 10(a) and 10(b) illustrate line scan lists which are produced by the scan list producing unit 706. FIG. 10(a) illustrates a line scan list of the scan line represented by SL1 in FIG. 8(b). FIG. 10(b) illustrates a line scan list of the scan line represented by SL2 in FIG. 8(b). In the figures, reference numeral 1011 designates a header of a line scan list of the scan line SL1, reference numeral 1012 designates an active cell indicating a first point on a side of the polygon from left on the scan line SL1, reference numeral 1013 designates an active cell indicating a second point on a side of the polygon from left on the scan line SL1, reference numeral 1021 designates a header of a line scan list on a scan line SL2, reference numeral 1022 designates an active cell indicating a first point on a side of the polygon from left on the scan line SL2, reference numeral 1023 designates an active cell indicating a second point on a side of the polygon from left on the scan line SL2, reference numeral 1024 designates an active cell indicating a third point on a side of the polygon from left on the scan line SL2, and reference numeral 1025 designates an active cell indicating a fourth point on a side of the polygon from left on the scan line SL2.
When a point on a side corresponding to an active cell is present on a scan line (Y=0), the scan list producing unit 706 sequentially produces a line scan list comprising an active cell indicating the point arranged in right direction (in the direction of ascending X from left end of the scan line) (X=0). On completion of production of a line scan list of the scan line Y=0, after subtracting 1 from a number of lines of the active cell which is added to the line scan list, the scan list producing unit 706 produces a line scan list of a scan line Y=1, and sequentially produces a line scan list for every scan line. In this way, the scan list producing unit 706 finds the line scan list in which a point on the side corresponding to each active cell that is present on the scan line for each scan line using the active list 713, for every scan line, to produce the scan list 714.
The rasterize unit 707 paints an interval from an odd numbered point on a side of the polygon from left to an even numbered point on a side of the polygon which are included in the scan list, for every scan line, thereby producing N times raster data 715 which is painted on the basis of an even odd rule.
Thereafter, in 1/N reducing processing in which a region including N.times.N (in this case 4.times.4) pixels of obtained N times raster data 715 is assumed as a cell to be output, the 1/N times reducing unit 708 produces raster data 716 which is obtained by representing a concentration of each 1/N reduced cell using values of 17 ranks, i.e., 0 to 16 which are represented by a number of painted pixels of all pixels (4.times.4=16 pixels) included in the cell. Thus obtained raster data 716 is input to a display device to display the polygon therein.
Thus, in the prior art high definition graphic display apparatus, after N times expansion of the polygon data, N times raster data is produced, and in 1/N reducing processing of the N times raster data, the raster data is produced, with the concentration of each cell represented by numbers of (N.times.N+1) ranks. Therefore, it is possible to make jagged edges of the displayed polygon unobvious. As a result, it is possible to display characters or graphics with high definition.
In the prior art high definition graphic display apparatus, when N times raster data is produced and 1/N times reducing processing of the N times raster data is performed, the raster data with the concentration of each cell represented by the number of (N.times.N+1) ranks is produced, thereby high definition graphic display can be performed. Therefore, it is necessary to expand the polygon data N times to produce the N times raster data, and many memories are required to produce the N times raster data.
In addition, it is time-consuming to produce N times raster data and perform operation processing for representing every cell concentration using a number of (N.times.N+1) ranks in 1/N reducing processing.
Further, in the case of applying the prior art high definition graphic display apparatus to an animation reproduction apparatus, since data to be transmitted to a display unit is raster data, transmission data and memories for recording (storing) the data becomes enormous.